1. Field of the Invention
This invention relates to a conveyor lift and service assembly for a mining machine and, more particularly, to a single actuator for lifting both the conveyor to an elevated position and lowering a service shoe into contact with the ground.
2. Description of the Prior Art
Continuous mining machines, as illustrated in U.S. Pat. No. 3,774,969, are used in underground mining operations to continuously dislodge solid material from the working face of a mine. A boom member extends forwardly from an elongated frame of the mining machine that is propelled through the mine on endless crawler tracks. The boom member is pivotally connected to the machine frame and rotatably supports a cutter drum assembly having peripherally extending cutter elements. The cutter drum extends transversely to the longitudinal axis of the machine frame. Upon rotation of the cutting elements solid material is dislodged from the mine face.
The dislodged material is moved rearwardly of the cutter drum assembly by a gathering device onto a receiving end of a conveyor mechanism that extends longitudinally on the machine frame. The conveyor mechanism includes a discharge end portion that is supported by a conveyor support frame for horizontal and vertical pivotal movement rearwardly of the mining machine. A main conveyor portion extends longitudinally on the machine frame from the gathering device to the conveyor discharge end portion.
The conveyor discharge end portion is pivotally connected to the conveyor support frame for horizontal and vertical pivotal movement. The conveyor discharge end portion is pivotal about a horizontal axis for vertical movement to the required height to transfer the mined material into a haulage vehicle and to adjust to the height of the mine entry. The discharge end portion is also connected to the main conveyor support frame for pivotal movement about a vertical axis for horizontal swinging movement relative to the main conveyor portion. Separate piston cylinder assemblies connected to the conveyor discharge end portion actuate the vertical and horizontal pivotal movement.
The conveyor discharge end portion is maintained in material receiving relation with a material haulage vehicle or another conveyor as the mining machine maneuvers the cutter drum assembly to dislodge solid material from the mine face. By maintaining the discharge end portion in material receiving relation with the haulage vehicle, the mined material is continuously conveyed from the mine face.
It is known to utilize conventional piston cylinder assemblies to actuate vertical and horizontal movement of the discharge conveyor. U.S. Pat. Nos. 3,095,080 and 3,826,353 disclose pivotal discharge conveyor assemblies. These conveyors are pivoted vertically by hydraulic cylinders mounted on the assembly frame.
U.S. Pat. Nos. 1,710,129 and 2,483,650 also disclose movable discharge conveyor assemblies. These conveyors are pivoted vertically by mechanical jacks which may be cranked into place against the ground to elevate the conveyor to the desired height.
It is also known to raise and lower the mining machine frame portion by service jacks or shoes to perform maintenance operations on the machine, such as adjusting the tension on the crawler tracks. Service jacks are also used to stabilize or anchor the mining machine frame on the mine floor.
The service jack or shoe is conventionally connected to the machine frame below the conveyor frame. The service shoe requires a separate piston cylinder assembly for lowering and raising into and out of contact with the mine floor. The piston cylinder assembly moves the shoe into contact with the mine floor with sufficient force to stabilize the position of the mining machine or raise the rear of the mining machine frame to an elevated position above the mine floor to provide access for conducting maintenance operations on the machine. U.S. Pat. Nos. 4,088,371 and 4,281,879 disclose stabilizing jacks of this general arrangement.
With the known stabilizing shoes for continuous mining machines, the shoes are positioned beneath the conveyor support frame at the rearward end portion of the body portion. One end of a piston cylinder is connected to the conveyor support frame and the opposite end or the extensible piston rod is connected to the shoe. One end of the shoe is, in turn, pivotally connected to the lower surface of the conveyor support frame.
A disadvantage with the known conveyor lift and service shoe assemblies is their inefficient layout on the mining machine. One set of piston cylinder assemblies is needed to lift the conveyor and a second set of assemblies is needed to actuate the service shoe. This adds to the cost and maintenance of mining machines because more parts and space are required on the machine to accommodate multiple sets of piston cylinder assemblies.
Therefore, there is a need on a mining machine for a single actuated conveyor lift/service shoe assembly that effectively performs the operations conventionally performed by two independent actuators.